Allow statements to auto close when consumed if no cache (#198)

spec/dummy_driver.cr

@@ -34,14 +34,20 @@ class DummyDriver < DB::Driver
     end
 
     def build_prepared_statement(query) : DB::Statement
+      assert_not_closed!
+
       DummyStatement.new(self, query, true)
     end
 
     def build_unprepared_statement(query) : DB::Statement
+      assert_not_closed!
+
       DummyStatement.new(self, query, false)
     end
 
     def last_insert_id : Int64
+      assert_not_closed!
+
       0
     end
 
@@ -54,12 +60,18 @@ class DummyDriver < DB::Driver
     end
 
     def create_transaction
+      assert_not_closed!
+
       DummyTransaction.new(self)
     end
 
     protected def do_close
       super
     end
+
+    private def assert_not_closed!
+      raise "Statement is closed" if closed?
+    end
   end
 
   class DummyTransaction < DB::TopLevelTransaction
@@ -114,6 +126,8 @@ class DummyDriver < DB::Driver
     end
 
     protected def perform_query(args : Enumerable) : DB::ResultSet
+      assert_not_closed!
+
       Fiber.yield
       @connection.as(DummyConnection).check
       set_params args
@@ -121,6 +135,8 @@ class DummyDriver < DB::Driver
     end
 
     protected def perform_exec(args : Enumerable) : DB::ExecResult
+      assert_not_closed!
+
       @connection.as(DummyConnection).check
       set_params args
       raise DB::Error.new("forced exception due to query") if command == "raise"
@@ -153,6 +169,10 @@ class DummyDriver < DB::Driver
     protected def do_close
       super
     end
+
+    private def assert_not_closed!
+      raise "Statement is closed" if closed?
+    end
   end
 
   class DummyResultSet < DB::ResultSet

spec/statement_spec.cr

@@ -43,6 +43,17 @@ describe DB::Statement do
       end
     end
 
+    it "should leave statements open to be reused if true" do
+      with_dummy_connection("prepared_statements=true&prepared_statements_cache=true") do |cnn|
+        rs = cnn.query("the query")
+        # do not close while iterating
+        rs.statement.closed?.should be_false
+        rs.close
+        # do not close to be reused
+        rs.statement.closed?.should be_false
+      end
+    end
+
     it "should not reuse prepared statements if false" do
       with_dummy_connection("prepared_statements=true&prepared_statements_cache=false") do |cnn|
         stmt1 = cnn.query("the query").statement
@@ -50,6 +61,31 @@ describe DB::Statement do
         stmt1.object_id.should_not eq(stmt2.object_id)
       end
     end
+
+    it "should close statements if false" do
+      with_dummy_connection("prepared_statements=true&prepared_statements_cache=false") do |cnn|
+        rs = cnn.query("the query")
+        # do not close while iterating
+        rs.statement.closed?.should be_false
+        rs.close
+        # do close after iterating
+        rs.statement.closed?.should be_true
+      end
+    end
+
+    it "should not close statements if false and created explicitly" do
+      with_dummy_connection("prepared_statements=true&prepared_statements_cache=false") do |cnn|
+        stmt = cnn.prepared("the query")
+
+        rs = stmt.query
+        # do not close while iterating
+        stmt.closed?.should be_false
+        rs.close
+
+        # do not close after iterating
+        stmt.closed?.should be_false
+      end
+    end
   end
 
   it "should initialize positional params in query" do